28-day intraocular pressure reduction with a single dose of brimonidine tartrate-loaded microspheres

Morgan V. Fedorchak, Ian P. Conner, Carlos A. Medina, Jeremy B. Wingard, Joel S. Schuman, Steven R. Little

    Research output: Contribution to journalArticle

    Abstract

    Treatment of glaucoma by intraocular pressure (IOP) reduction is typically accomplished through the administration of eye drops, the difficult and frequent nature of which contributes to extremely low adherence rates. Poor adherence to topical treatment regimens in glaucoma patients can lead to irreversible vision loss and increased treatment costs. Currently there are no approved treatments for glaucoma that address the inherent inefficiencies in drug delivery and patient adherence. Brimonidine tartrate (BT), a common glaucoma medication, requires dosing every 8-12h, with up to 97% of patients not taking it as prescribed. This study provides proof-of-principle testing of a controlled release BT formulation. BT was encapsulated in poly(lactic-co-glycolic) acid microspheres and drug release was quantified using UV-Vis spectroscopy. For invivo studies, rabbits were randomized to receive a single subconjunctival injection of blank (no drug) or BT-loaded microspheres or twice daily topical 0.2% BT drops. The microspheres released an average of 2.1±0.37μg BT/mg microspheres/day invitro. Invivo, the percent decrease in IOP from baseline was significantly greater in the treated eye for both topical drug and drug-loaded microspheres versus blank microspheres throughout the 4-week study, with no evidence of migration or foreign body response. IOP measurements in the contralateral, untreated eyes also suggested a highly localized effect from the experimental treatment. A treatment designed using the release systems described in this study would represent a vast improvement over the current clinical standard of 56-84 topical doses over 28 days.

    Original languageEnglish (US)
    Pages (from-to)210-216
    Number of pages7
    JournalExperimental Eye Research
    Volume125
    DOIs
    StatePublished - Aug 2014

    Keywords

    • Brimonidine
    • Controlled release
    • Glaucoma
    • Intraocular pressure
    • Microsphere
    • Polymer
    • Rabbit

    ASJC Scopus subject areas

    • Ophthalmology
    • Sensory Systems
    • Cellular and Molecular Neuroscience

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  • Cite this

    Fedorchak, M. V., Conner, I. P., Medina, C. A., Wingard, J. B., Schuman, J. S., & Little, S. R. (2014). 28-day intraocular pressure reduction with a single dose of brimonidine tartrate-loaded microspheres. Experimental Eye Research, 125, 210-216. https://doi.org/10.1016/j.exer.2014.06.013